3:20pm WA time will lead into the 6pm news - assuming Ch 7 has the news at 6pm in Perth. 3:20pm timeslots are common in the eastern states for that reason. It would be a 6:20pm start in Sydney; but AFL in Sydney is on 7Mate so the news isn't an issue.Good effort.
A few points here:
1. Eagles had the round 1 away in 2015. Normally, we shall have a home game the year after. Same principle applies to the Dockers.
2. Not sure if 3:20 pm on Sunday in Perth is suitable for TV?
3. Not sure if Dockers and Eagles play on Sunday in the same round with overlapping time slot is suitable for TV. Note that both teams draw a lot of advertisement for TV in Perth.
The St Kilda v Eagles game, being 1:10pm Melbourne time, would be all over 3:45pm Melbourne time which is 12:45pm in Perth; more than 2 hours before Freo v Swans starts - Melbourne is still in daylight savings time over that weekend. So there's no overlap.